It doesn't detract from Scripture. It detracts from the argument that the truth of the Church is contained exclusively in the Scripture.
Not without:
A. Knowing what Paul said to them, which we don't.
#2. Knowing that he said something to them that is important doctrinally but not contained in the Scriptures, which we also don't.
#3. I can think of no place in the bible where it suggests there is some important doctrine that is held by the church and not contained in the bible.